DESCRIPTION: (Applicant's Abstract) This study addresses several important issues regarding the long-term effects of treatment on substance abusing/dependent delinquents and their families, a population presenting complex and serious problems. These issues pertain to (a) physical health and psychosocial functioning, (b) utilization of substance abuse, mental health, and primary care services, and (c) cost effectiveness of treatment. The proposed study extends the follow-up from 1 year to 3-5 years, of an ongoing clinical trial with 118 substance abusing/dependent delinquents (R01DA-08029). The randomized trial, currently in its fourth of five years, compares multisystemic therapy (MST; Henggeler & Borduin, 1990; Henggeler et al., 1994) with usual community services. To date, this trial has been extremely successful. Project implementation goals have been met or surpassed regarding participant recruitment, research attrition, and treatment engagement. mising regarding MST effects on ultimate and instrumental outcomes. For example, compared with usual services, MST has reduced ont-of-home placements (primarily incarceration) by 50% (677 days vs. 1344 days) over an 11-month period. Thus, with annual evaluations of psychosocial functioning and monthly reviews of service utilization, the present application proposes to address the following specific aims. 1. Evaluate the long-term effects of MST on the physical health and psychosocial functioning of substance abusing/dependent delinquents. 2. Examine the effects of MST on service utilization patterns and track the "typical" course of service utilization among substance abusing/dependent delinquents assigned to the usual services condition. 3. Determine the cost-effectiveness of MST as compared with usual services.